The underground fuel tanks are filled from tank trucks by means of a large diameter hose which is sealingly coupled to the upper end of the fill pipe during the filling operation. Prior to delivery, the hose of the fuel truck traps a quantity of air therein. As a result, during delivery this quantity of air precedes the fuel flow into the underground fuel tank. Without a means for venting the air away from the fuel currently stored in the fuel tank, the air, as it enters and mixes with the fuel, causes underground fuel tank turbulence, increases foaming of fuel and increases vapor emissions.
Therefore, it is desirable to provide a device that addresses these concerns. Further, it is desirable to provide a device that is easily retrofitted in an existing drop tube and that can be easily installed with or without an automatic shutoff system currently disposed in the down tube. In addition, it is desirable to provide a device that prevents the vented air from returning to the fill pipe and escaping into the atmosphere.